Research has continued on the dipeptidyl aminopeptidase (DAP) method for polypeptide sequencing using gas chromatography-mass spectrometry (GC-MS) for dipeptide identification. The majority of work was focused on the enzymology of the method. Purification techniques were developed for the purification of DAP I, IV, and V. Hopefully, all polypeptides now will be degraded. The use of the DAP/GC-MS method appears to be a superior means for sequence analysis. Sensitivity and speed are the major assets of the technique.